Reflection

• How waves can be reflected off a boundary

  1. Draw ray diagrams

  2. Understand different types of reflection including specular and diffuse
• Waves aren't always reflected when they arrive at a boundary between two materials or mediums
• What can happen when a wave arrives at a boundary

  • Wave might be absorbed by the material
  • Wave could be transmitted and pass through the material
  • Wave could be reflected off the surface
• Which of the three things happens depends on the wavelength of the wave involved and the properties of the two materials
• Ray diagram


  Used to show reflection taking place
• Ray diagram


  • Start at the boundary between the two materials
  • Draw the incoming ray of light with an arrow
  • Draw the normal (perpendicular line)
  • Measure the angle of incidence
  • Angle of incidence = angle of reflection
  • Draw the reflected ray
• Point of incidence


  The point where the incoming ray touches the boundary
• Specular reflection


  Smooth, flat surface means all normals are in the same direction, so all incoming light rays are reflected in the same direction, giving a clear image
• Diffuse or scattered reflection

  Rough surface means normals point in different directions, so incoming light rays are reflected in all different directions, giving a scattered image
• In both specular and diffuse reflection, the angle of incidence is always equal to the angle of reflection